The present invention relates to a liquid filter, in particular for the lubricating oil for an internal combustion engine, which has a pot-shaped housing with a screw-on cover and a drain for residual liquid being provided in the screw-on cover. The invention also relates to a filter element which is suitable for installation in the liquid filter of the invention.
A filter of this type is known, for example, from U.S. Pat. No. 5,888,384 (=DE 196 44 647). This filter has a pot-shaped housing which has a downwardly directed installation opening for the filter cartridge. After the filter cartridge has been installed, a screw-on cover can be screwed into the installation opening. The inlet and outlet for the filter are located in the housing vessel, i.e., in the upper part of the filter housing. Therefore, the housing and in particular the screw-on cover are always filled with the liquid to be filtered even outside of operating time. This makes it difficult to change the filter cartridge because this residual liquid can enter the environment when the cover is being screwed off. Therefore, a drain plug is provided at the lowest point of the screw-on cover so that the drain plug can be loosened to remove the remaining liquid in the screw-on cover. This greatly facilitates the replacement of a filter cartridge.
The proposed liquid filter is used in particular as an oil filter for internal combustion engines, where the space situation is often very restricted because of other components in the engine compartment. Therefore, the are often problems associated with operation of the drain plug. Furthermore, the oil running out of the drain opening must be collected. This is often possible only under difficult conditions because of the tight installation situation because a collecting container with a sufficient volume cannot be placed beneath the drain opening.